Dozens of former high-ranking Vietnamese officials and prominent intellectuals continue to push for policy changes toward neighboring China as Hanoi makes final preparations for an upcoming party congress where personnel for the country's top jobs will be selected.

In an open letter to the Communist Party Politburo last week, more than 100 people — including some who served on the now-defunct prime ministerial advising board — cited China's massive artificial island-building spree in the South China Sea, which they called an "expansionism plot" in contested waters also claimed by Vietnam.

"China disregards international laws to step up its expansion over the South China Sea while using flowery words about peace and friendship [with Vietnam]. Not only does it blatantly encroach on Vietnamese territory, but also it causes instability to the region and the world," read the letter, obtained by VOA's Vietnamese Service.

Beijing has not responded to the criticism, but its officials have repeatedly said that China's construction is within the scope of its sovereignty.

Beijing 'not our friend'

Tran Bang, a veteran of the Vietnam-China border war, said he co-signed the letter because he is concerned by what he characterized as Hanoi's submissive attitude toward Beijing and its over-reliance on China.

FILE - Chinese President Xi Jinping, left, poses for a photo with Vietnam's Prime Minister Nguyen Tan Dung before their meeting at the Government Office in Hanoi, Nov. 5, 2015.

"Vietnam is stepping back from China's occupation plan over the South China Sea by agreeing with Beijing about maintaining the status quo in contested areas and by sustaining brotherly friendship between the two countries,” Bang said. “But Beijing is making aggressive moves on islands that it took away from Vietnam. It is not our friend."

Bang was bloodied last month during a crackdown on the anti-China protests during Chinese President Xi Jinping's visit to Vietnam.

During the visit, Xi was asked by the host's party chief Nguyen Phu Trong "not to militarize" and "to maintain peace" in the South China Sea.

According to a statement published on Vietnam's government website, the two sides are "committed to managing and solving maritime disputes so as not to impact on healthy and stable development of mutual ties."

Asked whether Vietnamese officials would reply to the letter, veteran Bang said he doubted it.

"The power is in their hands,” he said. “They are in better position than us. I am not sure they will heed our call, but we are all Vietnamese, so we want to continue a peaceful struggle.”

Ongoing struggle

Dozens of prominent members of Vietnam's Communist Party, some signers of the new letter to officials, last year called on leaders to file a legal case against Beijing with the International Tribunal on the Law of the Sea.

They wrote that Hanoi has paid a high price for conceding too much to China's demands.

"The more Vietnam steps back, the more China presses ahead," they wrote, adding that only a legal move can prove Vietnam's legitimacy over the disputed waters.

Vietnamese authorities never responded to the petition and they have not yet acknowledged the new letter.

Apart from the politically motivated movement, Vietnamese businesses have called for a boycott of low quality and unsafe Chinese products amid rising anti-China sentiment in the country.

This report was produced in collaboration with the VOA Vietnamese service.